The community engagement core aims to reduce health risks of residents in Maine who rely on domestic wells for water supply and who are exposed to arsenic, and other contaminants (Rn, U and Mn). The population relying on domestic wells in New England is subject to lifetime risks for lung and bladder cancers at a staggering 125 in 1 million, ranked second only to that of western states at 152 in 1 million. This risk is likely an underestimate because newer and more data from Maine and New Hampshire have found both higher As concentrations and a higher percentage of wells tested. In 17 towns of central Maine, the Columbia team has found that the percentage of domestic wells exceeding EPA MCL levels for As, Rn, U and Mn are 31%, 29%, 4% and 4%, respectively. Eight percent of well waters have As and Rn both exceeding MCLs. Arsenic testing and treatment will be promoted in this central Maine community before up scaling iin the state of Maine. Our goal is to establish a community engagement working model applicable for risk reduction of domestic well users in New England region, with the following specific aims: Aim 1. Identify and engage community stakeholders. In year one, a community advisory committee will be formed to guide implementation. Aim 2. Determine and reduce barriers for testing. By year five, the percentage of residents with private wells in central Maine who have their well water tested for arsenic will double compared to baseline. Aim 3. Determine whether dissemination of well water As test results has influenced the homeowner's decision to treat for As and determine and reduce barriers for treatment. By year five. The percentage of residents with private wells in central Maine who treat their well water for arsenic will double Aim 4. Raise awareness in the communities of other hazards in their well water: Rn, U and Man. Deliverable: Innovative community participatory tools for delivering outreach to change the behavior of residents of Maine (and beyond) at risk from arsenic exposure will be developed, tested, implemented and evaluated.